---
title: SAIF.Framework.Data.NHibernate overview
summary: High-level purpose, scope, and responsibilities for this library.
status: draft
owner: Framework
last_reviewed: 2026-09-15
library: SAIF.Framework.Data.NHibernate
reference_type: package
---

# SAIF.Framework.Data.NHibernate overview

> **Documentation context:** Packaged Component (NuGet)

`SAIF.Framework.Data.NHibernate` is a layered NHibernate ORM data-access library that implements and consumes — rather than defines — the unit-of-work/repository/session seam used by consuming applications, together with 42 FluentNHibernate entity mappings across 10 domain areas. The seam contracts — `IUnitOfWork`, `IRepository<TEntity>`, `ISessionHelper`, and `IDataEntity` — are supplied by the `SAIF.Framework.Core` package dependency (namespace `SAIF.Data`), not by the consuming application: this project's `RootNamespace` (`SAIF.Data.NHibernate`) nests under Core's `SAIF.Data` namespace, so C# enclosing-namespace lookup brings Core's types into scope without a `using` directive. This project's own `SAIF.Data.NHibernate.Interfaces` namespace is unrelated and holds only its 3 locally-declared interfaces (`IConfigurationFactory`, `ISessionStrategy`, `IUnitOfWorkFactory`).

## Purpose
- Provides engine-specific (Oracle and SQL Server) configuration and unit-of-work factories that build and cache NHibernate `Configuration`/`ISessionFactory` instances and hand out transaction-scoped units of work.
- Provides a generic CRUD/query repository surface (`Add`/`Update`/`Delete`/`Query`/`Get`/`Load`/`SystemDate`) usable against any entity mapped in the assembly, abstracting over stateful (`ISession`) and stateless (`IStatelessSession`) NHibernate session semantics behind a common `ISessionStrategy` seam.
- Declaratively maps 42 entities from the `SAIF.Data.Model.*` namespaces to their relational schema via FluentNHibernate `ClassMap<TEntity>` classes, discovered by assembly scanning rather than direct external consumption.
- Consumed by applications that need to wire up dependency injection against `IConfigurationFactory`/`IUnitOfWorkFactory`/`ISessionStrategy` to obtain database access for the 42 mapped entities.

## Responsibilities
- Build and cache engine-specific NHibernate configurations and session factories keyed by connection string.
- Own the unit-of-work transaction boundary (`Begin()`/`Commit()`/`Rollback()`).
- Provide generic repository CRUD/query operations over either session strategy.
- Supply engine-specific server-time retrieval with a local-clock fallback.
- Provide one domain-specific extension (`ImageRepositoryExtensions`) for Oracle sequence-based ID generation in the Imaging domain.

## Key components
- `IConfigurationFactory` / `ConfigurationFactoryBase` / `OracleConfigurationFactory` / `SqlServerConfigurationFactory`: build and cache engine-specific NHibernate `Configuration`/`ISessionFactory` instances.
- `IUnitOfWorkFactory` / `UnitOfWorkFactoryBase` / `OracleUnitOfWorkFactory` / `OracleStatelessUnitOfWorkFactory` / `SqlServerUnitOfWorkFactory`: construct `NHibernateUnitOfWork` instances per engine/session-strategy combination.
- `NHibernateUnitOfWork`: owns the transaction boundary and hands out `Repository<TEntity>` instances.
- `Repository<TEntity>` / `RepositoryBase<TEntity>`: generic CRUD + LINQ query surface over `ISessionStrategy`.
- `ImageRepositoryExtensions`: Oracle sequence-based ID generation extension methods for the Imaging domain.
- `Mappings/`: 42 `ClassMap<TEntity>` classes across 10 domain sub-folders (`Contacts`, `Deployment`, `Employee`, `Imaging`, `Menu`, `PDF`, `Preferences`, `Printing`, `Users`, `WebContext`).

## Related documentation
- [Index](index.md)
- [Architecture](architecture.md)
- [Dependencies](dependencies.md)
- [Operations and processes](operations-processes.md)
- [Business rules](business-rules.md)
- [Database tables](database-tables.md)
- [SQL catalog](sql/index.md)
- [API reference](api/index.md)

## Sources
- `SAIF.Framework.Data.NHibernate.csproj`
- `SAIF.Framework.Data.NHibernate.nuspec`